The present invention relates to railway vehicle couplers and more particularly to an improved railway coupler head having pulling lugs with compound fillets.
Both AAR Type E and Type F railway coupler heads are known to have pulling lugs. Further, both type coupler heads are known with upper and lower pulling lugs. The purpose of such pulling lugs is to receive the transferred draft load from an interfacing pulling surface of a knuckle which receives the transferred draft load from a knuckle of a mating coupler head.
The pulling lugs used currently on coupler heads have a knuckle interface surface comprising a substantially vertical pulling surface which extends into a radial fillet having a constant radius. The fillet connects the vertical pulling surface with a substantially horizontal surface adjacent a second radial fillet also having a constant radius at a raised boss for a thrower hole. With the introduction of high mileage and high load unit trains, forces acting on the pulling lugs of both type coupler heads have increased drastically.
A problem that has occurred in the currently used pulling lugs with the advent of increased mileage and loads, is the formation of fatigue cracks behind the pulling lug at the junction of the radial fillet with the horizontal surface. If these cracks become too great, the pulling lugs can fracture causing the coupled connection to fail. Such potential failure is a serious enough problem to consider modification of the coupler head design.